Key Ideas 1.2a – Importance levels of organization for structure and function include organelles, cells, tissues, organs, organ system, and whole organisms. 1.2b – Humans are complex organisms. They require multiple systems for digestion, respiration, reproduction, circulation, excretion, movement, coordination, and immunity. The systems interact to perform the life functions.
Organization of Organisms • Cell Tissue Organ Organ System Organism! • Cells – the basic units of structure and function in living things. Cells are specialized into tissues. • Tissues – a group of cells that are similar and organized into a functional unit. Tissues are groups of cells specialized to do certain jobs. • Ex. Muscle tissue, Nerve tissues
Organization of Organisms • Organs – a group of tissues that work together to perform a specific function • Example: Heart, Lungs, Kidneys • Organ Systems – a group of organs that work together to perform a specific function • Examples: Digestive system, nervous system • Organisms – a living thing • Examples: Humans!
Specialization of Cells • Specialization (differentiation) – the process that changes a stem cell into a specialized cell • Stem Cell – cells that have not yet been specialized • Almost every cell has a complete set of genes, but only those genes needed for the cell particular job are ‘turned on’ • Example: A red blood cell has all the genetic information needed to make nerve cells, bone cells and skin cells, but all of those ‘extra’ genes are turned off – only the red blood cell genes are turned on
Homeostasis Components of the human body, from organ systems to cell organelles, interact to maintain homeostasis Upsets in stability usually result in body system problems such as disease and death Physiology – study of the functions and activities of body systems
Types of Organ Systems • Nervous System • Endocrine System • Transport/Circulatory System • Respiratory System • Immune System • Excretory System • Digestive System • Reproductive System
Organ Systems Nervous system – regulates your body with electrochemical impulses Endocrine system – the system of the body that regulates overall metabolism, homeostasis, growth and reproduction Circulatory System – moves materials (water, nutrients, hormones, wastes) through the body to the cells that need them Respiratory System – breathing provides oxygen needed for chemical respiration (which releases energy from sugar)
Organ Systems Immune System – protect the body against pathogens (virus, bacteria and parasites) Excretory System – removes excess, unnecessary materials to help maintain homeostasis Digestive System – breakdown of complex food materials into simpler forms that an organism can use Reproductive System – group of organs and hormones that produces offspring
Digestive System • Digestion – Process by which large insoluble food molecules are broken down into smaller soluble molecules that can be used by the cells • Digestive system takes in and processes food to provide the body with chemicals and energy needed for metabolism • Nutrients – usable parts of food • Types of Digestion: • Extracellular Digestion – breakdown of molecules that takes place outside the body cells • Intracellular Digestion – breakdown of molecules in vacuoles inside the cell
Digestive System Made up of a continuous one-way-tube called the alimentary canal (gastrointestinal (GI) tract) Peristalsis – slow, rhythmic contractions that allow for food molecules to move though the GI tract Special areas about the tract change the complex food molecules into a simpler form so that they can pass from the GI tract and into all of the body cells
Organs of the Digestive System Mouth - the first part of the digestive system, where food enters the body. Chewing and salivary enzymes in the mouth are the beginning of the digestive process Salivary glands – glands located in the mouth that produce saliva. Saliva contains enzymes that break down carbohydrates into smaller molecules Esophagus – the long tube between the mouth and the stomach. It uses rhythmic muscles movements to force food from the throat into the stomach Liver – a large organ located above and in front of the stomach. It filters toxins from the blood, and makes bile (which breaks down fats) and some bloods proteins Stomach – a sack-like, muscular organ that is attached to the esophagus. Both chemical and mechanical digestion takes place in the stomach. When food enters the stomach, it is churned in a bath of acids and enzymes
Organs of the Digestive System • Pancreas – an enzyme-producing gland located below the stomach and above the intestines. Enzymes from the pancreas help in the digestion of carbohydrates, fats and proteins in the small intestine • Large intestine – where water, vitamins and minerals are absorbed into the blood stream • Small intestine – where food digestion is completed and digested nutrients are absorbed into the blood stream • Rectum – the lower part of the large intestine, where feces are stored before they are excreted • Anus – the opening at the end of the digestive system from which feces (waste) exits the body
Digestive System The Digestion Process - What happens to your food as it travels through the digestive system? - http://www.youtube.com/watch?v=08VyJOEcDos
Digestive Process Food is first ingested by the mouth. The tongue and teeth break up the food into smaller pieces. Allows for mechanical digestion, which increases the surface area of the food so chemical digestion can begin Salivary glands secrete saliva, a mucus that moistens food making it easier to swallow. Saliva contains enzyme ptyalin, which starts the chemical digestion of starches. Starches are the major energy sources for the body. Swallowed food goes into the esophagus and travels to the stomach that churns and mashes food into a thick soupy mixture called chyme. Glands in the stomach lining secrete gastric juice and hydrochloric acid to assist with chemical digestion.
Digestive Process Partly digested food leaves the stomach and enters the small intestine, where food digestion is completed and digested nutrients are absorbed into the blood steam. Most chemical digestion takes place in the small intestine, not in the stomach. Digestion is accomplished by action of enzymes produced by intestinal glands and pancreas. Villi are tiny, finger-like projections on the intestinal wall that increase the surface area of the small intestine for better absorption of end products of digestion
Digestive Process Undigested foods called wastes pass from the small intestine into the large intestine (colon). Water, some vitamins, minerals are absorbed into the blood stream. The remaining undigested substances, called feces, are stored in the lower end of the large intestine called the rectum. Feces are eliminated from the body (egestion) through the anus
Digestive System Vocabulary Taste Buds – group of cells located in the tongue and roof of the mouth that differentiate between sweet, sour, salty and bitter tastes Proteins – needed to build and repair body tissue and provide energy when major energy sources are missing from the diet Rennin – an enzyme that begins the chemical digestion of milk protein Bile – made by the liver and stored in the gall bladder, prepares fats and oils for digestion Lipases – enzyme that digest fats and oils and breaks fats and oils down into smaller pieces Fats – important energy source
Mechanical & Chemical Digestion Mechanical Digestion – food is physically cut, ground and torn into smaller pieces; it increases surface area of the food particles preparing them for chemical digestion Chemical Digestion – large organic molecules are chemically split into small simple molecules; requires a specific enzyme Enzyme – catalyze (speed up or slow down) chemical reactions Digestive enzymes help break down food and must be present for digestion to occur
Digestive System Disorders Ulcers – an open, painful sore in the stomach lining, can bleed and something eats through the stomach wall. Tooth Decay – mouth bacteria can cause breakdown of teeth Appendicitis – an infection of the appendix, treated by surgically removing the appendix